Hydrolyzable silylated polymers are useful to make room temperature and moisture curable compositions, such as coatings, adhesives, gaskets, sealants and the like. Inherently fast moisture cure characteristics of alpha-substituted alkyl hydrolyzable silyl-terminated polyurethane polymers, in comparison to their gamma-substituted counterparts, make them desirable, as they potentially allow the use of lesser amounts of environmentally hazardous tin catalysts and offer Hazardous Air Pollutants (HAPs) free curing compositions.
The preparation of hydrolyzable silylated polymers is generally known in the art. A commonly used commercial method for making hydrolyzable silylated polymers generally involves two steps. The first step comprises the synthesis of isocyanato-substituted hydrolyzable silane by heating the corresponding carbamato-functional hydrolyzable silane at elevated temperatures and under reduced pressures. This step requires the inefficient and costly cracking of the carbamato-functional silane in specialized reactors that allow for the parallel and efficient separation of thereby formed isocyanato-functional silane from its reactants and byproducts, and subsequent purification. Due to high reactivity of the isocyanato-substituted silanes, special care is required to prevent the polymerization of the isocyanato group and hydrolysis of the silyl group during storage of these materials, prior to use. In the second step, the isocyanato-functional silane is reacted with active hydrogen containing polymers, such as polyols, in a differently configured reactor.
Inventively, it has now been discovered that, one can make hydrolyzable silylated polymers in one-step, without the need to first make, purify and store the isocyanato-functional silanes and subsequently to react them with corresponding active hydrogen-functionalized polymers.